Beware the fake "dislike" button that scammers are using to try to get Facebook users to hand over personal information, according to security firm Sophos.

"It's the latest survey scam spreading virally across Facebook, using the tried-and-tested formula used in the past by other viral scams including 'Justin Bieber trying to flirt,' 'Student attacked his teacher and nearly killed him,' and 'the biggest and scariest snake,' and the 'world's worst McDonald's customer,'" says Graham Cluley, senior technology consultant at Sophos, in his blog.  

In the case of the fake dislike button, the application encourages users to "add a 'dislike' feature to your Facebook. You will have the ability to dislike any of your friends' statuses. Simply click the install button to use this application." But Sophos is warning Facebook users against doing that.

Anyone who gives the app permission to run will find "it silently updates your Facebook status to promote the link that tricked you in the first place, thus spreading the message virally to your Facebook friends and online contacts," Cluley explains in his blog.

Facebook

The application asks the victim to complete an online survey which makes money for the scammers, he adds. Facebook users today have a legitimate "like" button that Facebook provides, and some users have asked for a "dislike" button as well. So the scammers are using this enticement to trick Facebook users, Cluley points out.

Giving away personal information in a survey and allowing an application access to your profile is extremely risky, Cluley warns, adding "Facebook users need to wise up to this rather than just clicking on links that they see, just because they appear to be from a trusted source." Anyone who falls for this trick should delete references to the dislike button and remove the application.